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61.
Isabelle Jourdain Hannah C. Dooley Takashi Toda 《Traffic (Copenhagen, Denmark)》2012,13(11):1481-1495
The exocyst complex tethers post‐Golgi secretory vesicles to the plasma membrane prior to docking and fusion. In this study, we identify Sec3, the missing component of the Schizosaccharomyces pombe exocyst complex (SpSec3). SpSec3 shares many properties with its orthologs, and its mutants are rescued by human Sec3/EXOC1. Although involved in exocytosis, SpSec3 does not appear to mark the site of exocyst complex assembly at the plasma membrane. It does, however, mark the sites of actin cytoskeleton recruitment and controls the organization of all three yeast actin structures: the actin cables, endocytic actin patches and actomyosin ring. Specifically, SpSec3 physically interacts with For3 and sec3 mutants have no actin cables as a result of a failure to polarize this nucleating formin. SpSec3 also interacts with actin patch components and sec3 mutants have depolarized actin patches of reduced endocytic capacity. Finally, the constriction and disassembly of the cytokinetic actomyosin ring is compromised in these sec3 mutant cells. We propose that a role of SpSec3 is to spatially couple actin machineries and their independently polarized regulators. As a consequence of its dual role in secretion and actin organization, Sec3 appears as a major co‐ordinator of cell morphology in fission yeast . 相似文献
62.
Direct hemin transfer from IsdA to IsdC in the iron-regulated surface determinant (Isd) heme acquisition system of Staphylococcus aureus 总被引:1,自引:0,他引:1
Liu M Tanaka WN Zhu H Xie G Dooley DM Lei B 《The Journal of biological chemistry》2008,283(11):6668-6676
The iron-regulated surface determinants (Isd) of Staphylococcus aureus, including surface proteins IsdA, IsdB, IsdC, and IsdH and ATP-binding cassette transporter IsdDEF, constitute the machinery for acquiring heme as a preferred iron source. Here we report hemin transfer from hemin-containing IsdA (holo-IsdA) to hemin-free IsdC (apo-IsdC). The reaction has an equilibrium constant of 10 +/- 5 at 22 degrees C in favor of holo-IsdC formation. During the reaction, holo-IsdA binds to apo-IsdC and then transfers the cofactor to apo-IsdC with a rate constant of 54.3 +/- 1.8 s(-1) at 25 degrees C. The transfer rate is >70,000 times greater than the rate of simple hemin dissociation from holo-IsdA into solvent (k transfer = 54.3 s(-1) versus k -hemin = 0.00076 s(-1)). The standard free energy change, Delta G 0, is -27 kJ/mol for the formation of the holo-IsdA-apo-IsdC complex. IsdC has a higher affinity for hemin than IsdA. These results indicate that the IsdA-to-IsdC hemin transfer is through the activated holo-IsdA-apo-IsdC complex and is driven by the higher affinity of apo-IsdC for the cofactor. These findings demonstrate for the first time in the Isd system that heme transfer is rapid, direct, and affinity-driven from IsdA to IsdC. These results also provide the first example of heme transfer from one surface protein to another surface protein in Gram-positive bacteria and, perhaps most importantly, indicate that the mechanism of activated heme transfer, which we previously demonstrated between the streptococcal proteins Shp and HtsA, may apply in general to all bacterial heme transport systems. 相似文献
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M S Melzer R T Christian J F Dooley B Schumann H L Su S Samuels 《Mutation research》1983,116(3-4):281-287
Knox reported that the short-term effects of the carcinogen methylnitrosourea (MNU) were due to the formation of its decomposition product, the cyanate ion. He showed that cell survival and DNA synthesis decreased as the concentration of MNU and the cyanate ion (NCO-) increased in the medium. Further, the product of MNU decomposition comigrated with NCO- when added to his chromatographic test system. However, Knox did not study the mutagenicity of MNU or its breakdown products. We compared the mutagenicity of MNU and potassium cyanate (KNCO) in mammalian cells. Our results demonstrate that, although it is toxic to cells, KNCO does not induce ouabain-resistant mutants in cultured Chinese hamster cells (V79). 相似文献
66.
Chromosome 16 microdeletion in a patient with juvenile neuronal ceroid lipofuscinosis (Batten disease). 总被引:1,自引:0,他引:1
P E Taschner N de Vos A D Thompson D F Callen N Doggett S E Mole T P Dooley P G Barth M H Breuning 《American journal of human genetics》1995,56(3):663-668
The gene that is involved in juvenile neuronal ceroid lipofuscinosis (JNCL), or Batten disease--CLN3--has been localized to 16p12, and the mutation shows a strong association with alleles of microsatellite markers D16S298, D16S299, and D16S288. Recently, haplotype analysis of a Batten patient from a consanguineous relationship indicated homozygosity for a D16S298 null allele. PCR analysis with different primers on DNA from the patient and his family suggests the presence of a cytogenetically undetectable deletion, which was confirmed by Southern blot analysis. The microdeletion is embedded in a region containing chromosome 16-specific repeated sequences. However, putative candidates for CLN3, members of the highly homologous sulfotransferase gene family, which are also present in this region in several copies, were not deleted in the patient. If the microdeletion in this patient is responsible for Batten disease, then we conclude that the sulfotransferase genes are probably not involved in JNCL. By use of markers and probes flanking D16S298, the maximum size of the microdeletion was determined to be approximately 29 kb. The microdeletion may affect the CLN3 gene, which is expected to be in close proximity to D16S298. 相似文献
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JC. Brisset F. Gazeau C. Corot N. Nighoghossian Y. Berthezène E. Canet-Soulas M. Wiart 《IRBM》2018,39(2):93-102
Background
Inflammation is a share process in atherosclerosis and stroke and is thought to be a key player in the evolution of these diseases. Ten years ago, inflammation imaging with magnetic resonance imaging (MRI) was considered very promising for both pre-clinical and clinical studies of atherosclerosis and stroke.Contribution
We report here contributions to the field of inflammation imaging with USPIO-enhanced MRI. The goal was to investigate the life cycle of USPIOs in the body, and how the MRI signal has been impacted during their bio-interactions and bioprocessing. Those mechanisms were applied to pre-clinical longitudinal studies of inflammation in atherosclerosis and at the acute stage of ischemic stroke thus allowing the monitoring of treatment effects.Conclusion
This review presents the contribution of the collaborative research project under the “TecSan” grant from the French Research Agency (ANR) as well as pre-clinical and clinical perspectives of USPIO's inflammation MRI in atherosclerosis and stroke. 相似文献70.
Nonneutral evolution of tandem repeats in the mitochondrial DNA control region of lagomorphs 总被引:7,自引:0,他引:7
Casane D; Dennebouy N; de Rochambeau H; Mounolou JC; Monnerot M 《Molecular biology and evolution》1997,14(8):779-789
The mitochondrial DNA of the European rabbit (Oryctolagus cuniculus)
contains a tandem array of 153-bp repeats in the vicinity of the
replication origin of the H-stand. Variation among molecules in the number
of these repeats results in inter- and intraindividual length polymorphism
(heteroplasmy). Generally, in an individual, one predominant molecular type
is observed, the others representing a low percentage of the mtDNA content.
At the tissue level, we observe a particular distribution of this
polymorphism in the gonads compared with liver, kidneys, or brain, implying
a relationship between the differentiation status of the cells and the
types of new mtDNA molecules which appear and accumulate during lifetime.
Similar tandem repeats were also found in the mtDNA noncoding region of
European hares (Lepus europaeus), a cottontail (Sylvilagus floridanus), and
a pika (Ochotona rufescens). The lengths and the sequences of these units
evolve rapidly and in a concerted way, but the number of repeats is
maintained in a narrow range, and an internal 20-bp segment is highly
conserved. Constraints restrict the evolution of the primary sequence of
these repeated units, the number of which is probably controlled by a
stabilizing selection.
相似文献